Colorectal cancer follow-up: perspectives for future studies.

This paper reviews some of the issues involved in the planning and execution of studies to assess the effect of different follow-up strategies for colorectal cancer patients. Mathematical models and many previous studies have failed to indicate strong support for the hypothesis that extensive follow-up leads to an increase in survival rates. In order to assess the best follow-up strategies, at present, within the different Dukes' stages, extremely large trials are required and none of the previous studies have satisfied this criterion, though recently planned studies will, if recruitment targets are met. The large number of patients required, the length of time the study must run, existing accepted follow-up practices in different countries, and the difficulty of managing patients on different follow-up strategies within the same centre all pose problems for the design of a randomized trial. These are not insurmountable, but do contribute to a possible downfall of a large multicentre randomized trial of follow-up strategies. Although such a trial will require considerable international cooperation it will have enormous benefits and implications if it is managed and completed successfully. Copyright 2000 Harcourt Publishers Ltd.